1. Field of the Invention
The present invention relates to a safety gas container and more particularly, a safety gas container for holding a gas of explosive nature, such as carbon dioxide gas, oxygen and a liquefied fuel gas, the container being provided with a valve for permitting the content to escape at such a small rate as to avoid an abrupt ejection of the content which would cause a reaction on the container thereby to propel it forward.
2. Description of the Prior Art
A typical example is disclosed in U.S. Pat. No. 4,219,126. The disclosed container is provided with a recess in the sealing plate, the recess having a thin bottom wall rupturable under the rise in internal pressure due to overheating. The disclosure teaches that when the internal pressure abnormally rises an invisible crack occurs in the bottom of the recess, through which the content gradually leaks thereby to reduce the internal pressure.
As a result of experiments, however, it has been found out that the crack develops from the bottom to the inside wall of the recess, thereby finally causing the whole recess to rupture into a hole. Consequently the content ejects through the hole, thereby causing the reaction of ejection upon the container. It is reported that there have been several accidents in which people were injured by the flying container. This is mainly caused by the structure in which the gas is straightly ejected along the axis of the container. It is therefore difficult to prevent the container from flying under the reaction.
Another disadvantage of the disclosed invention is that it is difficult to equalize the bottom thicknesses of the recesses. Normally the bottom wall is made as thin as 0.3 mm so that it readily fructures under the rise in internal pressure. As a result it is unavoidable that some containers have recess whose bottom walls are relatively thick while others have those which have relatively thin bottom walls. Thus the safety critical temperature has to be low.
A further disadvantage of the prior invention is that the thin bottom walls of the recesses are liable to corrosion because of a gathering water, such as rain. The corroded bottom is likely to fracture even at normal pressures.